/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.10.31 00:03:56
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

template< int MOD >
struct mint {
public:
    long long x;
    mint(long long x = 0) :x((x%MOD+MOD)%MOD) {}
    mint(std::string &s) {
        long long z = 0;
        for (int i = 0; i < s.size(); i++) {
            z *= 10;
            z += s[i] - '0';
            z %= MOD;
        }
        this->x = z;
    }
    mint& operator+=(const mint &a) {
        if ((x += a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator-=(const mint &a) {
        if ((x += MOD - a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator*=(const mint &a) {
        (x *= a.x) %= MOD;
        return *this;
    }
    mint& operator/=(const mint &a) {
        long long n = MOD - 2;
        mint u = 1, b = a;
        while (n > 0) {
            if (n & 1) {
                u *= b;
            }
            b *= b;
            n >>= 1;
        }
        return *this *= u;
    }
    mint operator+(const mint &a) const {
        mint res(*this);
        return res += a;
    }
    mint operator-() const {return mint() -= *this; }
    mint operator-(const mint &a) const {
        mint res(*this);
        return res -= a;
    }
    mint operator*(const mint &a) const {
        mint res(*this);
        return res *= a;
    }
    mint operator/(const mint &a) const {
        mint res(*this);
        return res /= a;
    }
    friend std::ostream& operator<<(std::ostream &os, const mint &n) {
        return os << n.x;
    }
    friend std::istream &operator>>(std::istream &is, mint &n) {
        long long x;
        is >> x;
        n = mint(x);
        return is;
    }
    bool operator==(const mint &a) const {
        return this->x == a.x;
    }
    bool operator!=(const mint &a) const {
        return this->x != a.x;
    }
    mint pow(long long k) const {
        mint ret = 1;
        mint p = this->x;
        while (k > 0) {
            if (k & 1) {
                ret *= p;
            }
            p *= p;
            k >>= 1;
        }
        return ret;
    }
};
constexpr int MOD = 1e9 + 7;
template< class T >
struct Matrix {
    std::vector< std::vector< T > > A;
    Matrix() {}
    Matrix(size_t n, size_t m) : A(n, std::vector< T >(m, 0)) {}
    Matrix(size_t n) : A(n, std::vector< T >(n, 0)) {};
    size_t height() const {
        return (A.size());
    }
    size_t width() const {
        return (A[0].size());
    }
    inline const std::vector< T > &operator[](int k) const {
        return (A.at(k));
    }
    inline std::vector< T > &operator[](int k) {
        return (A.at(k));
    }
    static Matrix I(size_t n) {
        Matrix mat(n);
        for (int i = 0; i < n; i++) mat[i][i] = 1;
        return (mat);
    }
    Matrix &operator+=(const Matrix &B) {
        size_t n = height(), m = width();
        assert(n == B.height() && m == B.width());
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                (*this)[i][j] += B[i][j];
        return (*this);
    }
    Matrix &operator-=(const Matrix &B) {
        size_t n = height(), m = width();
        assert(n == B.height() && m == B.width());
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                (*this)[i][j] -= B[i][j];
        return (*this);
    }
    Matrix &operator*=(const Matrix &B) {
        size_t n = height(), m = B.width(), p = width();
        assert(p == B.height());
        std::vector< std::vector< T > > C(n, std::vector< T >(m, 0));
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                for (int k = 0; k < p; k++)
                    C[i][j] = (C[i][j] + (*this)[i][k] * B[k][j]);
        A.swap(C);
        return (*this);
    }
    Matrix operator+(const Matrix &B) const {
        return (Matrix(*this) += B);
    }
    Matrix operator-(const Matrix &B) const {
        return (Matrix(*this) -= B);
    }
    Matrix operator*(const Matrix &B) const {
        return (Matrix(*this) *= B);
    }
    bool operator==(const Matrix &B) const {
        assert(this->A.size() == B.A.size() && this->A[0].size() == B.A[0].size());
        int n = this->A.size();
        int m = this->A[0].size();
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                if (this->A[i][j] != B.A[i][j]) return false;
        return true;
    }
    bool operator!=(const Matrix &B) const {
        return !(*this == B);
    }
    friend std::ostream &operator<<(std::ostream &os, Matrix &p) {
        size_t n = p.height(), m = p.width();
        for (int i = 0; i < n; i++) {
            os << "[";
            for (int j = 0; j < m; j++) {
                os << p[i][j] << (j + 1 == m ? "]\n" : ",");
            }
        }
        return (os);
    }
    
    T determinant() {
        Matrix B(*this);
        assert(width() == height());
        T ret = 1;
        for (int i = 0; i < width(); i++) {
            int idx = -1;
            for (int j = i; j < width(); j++) {
                if (B[j][i] != 0) idx = j;
            }
            if (idx == -1) return (0);
            if (i != idx) {
                ret *= -1;
                swap(B[i], B[idx]);
            }
            ret *= B[i][i];
            T vv = B[i][i];
            for (int j = 0; j < width(); j++) {
                B[i][j] /= vv;
            }
            for (int j = i + 1; j < width(); j++) {
                T a = B[j][i];
                for (int k = 0; k < width(); k++) {
                    B[j][k] -= B[i][k] * a;
                }
            }
        }
        return (ret);
    }
    
    
    Matrix pow(ll k) const {
        auto res = I(A.size());
        auto M = *this;
        while (k > 0) {
            if (k & 1) {
                res *= M;
            }
            M *= M;
            k >>= 1;
        }
        return res;
    }
};
int main() {
    ll a,b,n;cin >> a >> b >> n;
    if (n == 0) {
        cout << 2 << endl;
        return 0;
    }
    else if (n == 1) {
        cout << 2 * a % MOD << endl;
        return 0;
    }
    Matrix<mint<MOD>> mat(2);
    mat[0][0] = mint<MOD>(2 * a), mat[0][1] = mint<MOD>(-a*a+b);
    mat[1][0] = 1;
    mat = mat.pow(n-1);
    cout << mat[0][0] * 2 * a + mat[0][1] * 2 << endl;
    return 0;
}